Internal combustion engines use oil pans disposed beneath the crankcase of an engine to collect and store oil as a source of oil for an oil pump that distributes it under pressure throughout the engine. The crankcase volume is at least partially defined by a cylinder block having a crankshaft rotatably mounted thereto. The crankshaft mechanically engages pistons, reciprocally movable within bores defined by the cylinder block, through a link such as a connecting rod. The rotational motion of the crankshaft coupled with the reciprocal motion of the pistons combine to cause turbulent airflow within the crankcase. This airflow is sometimes referred to as “windage” and may be pronounced at high engine speeds. The windage may also entrain oil thrown or ejected from journal bearings such as main bearings, which support the crankshaft within the cylinder block, and the rod bearings, which support the connecting rod on the crankshaft. Additionally, the windage may entrain oil already in the sump or collection volume of the oil pan. The windage along with the entrained oil in the crankcase volume operates to increase drag or rotational resistance of the rotating crankshaft thereby reducing the efficiency of the engine. This loss in efficiency may lead to reduced engine performance. Additionally, the oil within the crankcase volume may entrain an amount of air causing the oil within the sump to become aerated. The increased volume of the aerated oil may cause additional oil to become entrained by the windage thereby leading to a “runaway” condition under certain engine operating modes.
Engineers have employed oil deflectors, often referred to as “windage trays”, to isolate the effects of the crankshaft and other rotating parts on the oil contained within the oil pan. The windage tray is disposed beneath the rotating parts of the engine and operates to create a barrier between these rotating parts and the oil collection volume of the oil pan. Windage trays are typically mounted to main caps supporting the crankshaft, between the oil pan and the cylinder block, or to the oil pan. Prior art windage trays are simply a panel of metal or molded plastic.
More recently, efforts have been made to reduce the noise, vibration, and harshness, or NVH, of vehicles. One of the main sources of NVH is the internal combustion engine. Although the prior art windage tray may serve a valuable function in controlling engine efficiency loss due to windage, the windage tray and oil pan can be a source of radiated noise. The windage tray may radiate noise due to vibrations caused by the high-speed impact of oil thrown from the crankshaft as well as vibrations transmitted to the windage tray through the part of the engine to which the windage tray is mounted. While both solid metal and molded plastic windage trays may be effective at reducing windage losses within the crankcase, they may create a resonance due to interaction with other engine components thereby increasing the overall engine noise.